Field of the Invention
The present invention relates to an assembly of two parts which are articulated to each other by a hinge of the type with assisted opening/closing, also known as a snap action type hinge. An assembly of this type may, in particular, be formed from a closure element of the type comprising a body on which a closure cap is articulated. Alternatively, it may be a container of the type comprising a lid articulated to a base. A container of this type may have the form of a case of the make-up-case type, or a pot, or any other form of container capable of being closed by an articulated lid.
Particularly as regards closure elements, it is known to produce such elements in two unitarily molded polyethylene or polypropylene parts. The two parts can be folded about an axis and joined by film hinges with at least one intermediate element arranged between them. The intermediate element is capable of forming a spring in order, after an unstable balance position has been passed, to bias the cap of the closure element into the closed or substantially closed or open position. With a configuration of this type, the axis of articulation is defined by the film hinge which may break after having been handled a number of times. Accordingly, a structure of this type is not the most appropriate for articulating the lid of a case to its base, particularly for reasons of strength and appearance. The same applies to articulating a lid to a pot or another container of the same type.
EP-B-699,591 shows a structure in which the spring function is provided by a member of a lid which, during assembly, is positioned in a corresponding housing of the base to which the lid is articulated. The articulation axis is defined by conventional film hinges. Moreover, with this type of design only opening is assisted. Upon closure, the member forming the spring exerts a return force opposed to the closure movement.
It is known, particularly from U.S. Pat. No. 4,158,902, to provide tabs on a lid, which tabs form a spring and are capable of interacting with members of the same type carried by a base to which the lid is articulated. The articulation axis about which the lid pivots is formed from one or more film hinges.
U.S. Pat. No. 4,124,151 describes a bottle cap of the type comprising a body intended to be mounted on a container and a cap capable of reversibly closing an orifice in the body of the cap. In an intermediate position between the open position and the closed position, the distance between two ends of an elastic linking strip passes a minimum value, the linking strip in this position being compressed so as to form a spring. A configuration of this type is perceived by consumers to be awkward to open and to close. Moreover, it is relatively weak.
It is one object of the present invention to produce an assembly of two parts which are articulated to each other, totally or partially solving the problems mentioned above.
It is a further object of the present invention to produce an assembly, articulated by a spring-effect hinge, which is reliable and economical to produce.
According to the invention, the above and other objects are achieved by a molded one piece assembly, including a first part, and a second part articulated to the first part by a spring-effect hinge. At least one linking strip provides assisted opening and closing of the assembly about a fixed articulation axis (A). The first part forms at least one member capable, after molding, of being placed in engagement with at least one corresponding member formed by the second part so as to form at least one articulation zone about the axis (A), the linking strip or strips being capable, in an intermediate position between an open position and a closed position of the assembly, of crossing the axis (A).
There is thus produced an articulated assembly of which the opening and closing are assisted. The assembly thus produced offers all the advantages of structures articulated as a single piece, particularly in terms of manufacturing cost. Moreover, the axis of articulation has, in terms of robustness and appearance, characteristics which are similar to those of articulations of the attached-pin type. The ease of use afforded by a structure in which the linking strip intersects the axis is generally judged to be more satisfactory than that afforded by a structure of the type described in the above mentioned U.S. Pat. No. 4,124,151.
According to an advantageous characteristic of the invention, the linking strip comprises a first end integral with the first part and a second end integral with the second part, the distance between the first and second ends passing a maximum value in the intermediate position. Thus, in the closed position of the assembly, the linking strip intersects a closure plane (PF). By passing through the intermediate position, it is subject to maximum tension. After passing through the intermediate position, according to a relative movement of the first and second parts in a first direction, the linking strip elastically returns the second part into the closed or substantially closed position. After passing through the intermediate position, in a direction which is opposite from the first, the linking strip elastically returns the second part to the open position.
According to a particular embodiment, the assembly according to the invention comprises a linking strip positioned between two articulation zones defining the axis (A). According to an alternative, the assembly comprises two linking strips separated by an articulation zone defining the axis (A).
Preferably, the member formed by the first part consists of a pin, and the member formed by the second part consists of a housing oriented parallel to the pin and intended to receive the pin via an opening oriented parallel to the pin, or vice versa.
The opening of the housing or housings is delimited by two edges and advantageously extends over an angle such that the pin elastically deforms the edges upon snap-fitting of the pin in the housing. In this way, the risk of the pin becoming detached from its housing is substantially reduced.
The piece may be formed from a single thermoplastic material, for example a polyethylene or a polypropylene. Alternatively, it may, for example, be produced by dual injection and is formed from at least two physically/chemically compatible materials, i.e., materials that are capable, in the molten state, of together forming physical/chemical bonds. By way of example, it may be formed from a first thermoplastic material forming the linking strip or strips and from a second thermoplastic material forming the remainder of the piece. Thus, the linking strips are formed by a first material having the necessary elasticity characteristics for their proper functioning while the remainder of the assembly has the characteristics, particularly of hardness or of shine, which are necessary for the appearance sought. A configuration of this type is particularly suitable if the assembly is to form a case, particularly a make-up case.
The first material may, in particular, be an elastomer (particularly a thermoplastic elastomer of the SANTOPRENE(copyright) OR KRATON(copyright) type), it being possible for the second material to be, for example, a polypropylene or a polyethylene.
According to a first embodiment, the assembly according to the invention forms a closure element, the first part forming a body intended to be mounted (in particular by snap-fitting or screwing) on a container, the body delimiting at least one exit passage in communication with an opening of the container, the second part being formed by a cap capable of temporarily closing the exit passage.
According to a second embodiment, the assembly consists of a container, the first part constituting a receptacle delimiting at least one compartment capable of containing a product, the second part forming a lid capable of covering the at least one compartment. Advantageously, the container allows reversible locking of the lid on the receptacle in the closed position.
Preferably, the container is in the form of a substantially flat case, the base of which delimits at least one compartment for receiving a product, particularly in solid or pulverulent form. A product of this type may, for example, be a make-up product.